[abc80] Super Smartaid Cartridge

[H. Peter Anvin]

On 4/23/19 12:46 PM, Anders Sandahl wrote:
> I'll bet that all the circuits turns out to be the same as on the magnum
> version. The board it self looks the same, the patches are different.
> Different sizes on one of the ERPOM's and a piggybacked 74ls74 on one
> place.

Right, 27128 = 16Kx8. The extra 74LS74 (dual D flip flip) is presumably
used for the extra address pins, which, together with the blue wires and
"SUPER" marking, very much supports the idea that it is largely the same
board, although it seems to be a different version: the lines are
clearer, and the alignment of the larger EPROM has changed.

Well, this makes it easier...

N82S131 is a bipolar prom (512x4), which probably indicates that, just
like ABC80 itself, it uses a PROM for address decoding. Reading out this
PROM is going to be important.

I'm amused at seeing a single 74HC IC on that board, a 74HC32. It's not
even a TTL-compatible 74HCT (74HC can drive TTL, but not the other way
around -- at least not reliably -- unless Vdd is reduced sufficiently.)

I am guessing it is a simple drop-in mistake and that it worked well
enough; the circuit is a quad OR gate and it must get its inputs from
somewhere...

MB8416A is just Fujitsu's part number for an 6116 SRAM.

	-hpa